In accordance with the introduction of FD (full dimension) MIMO (multiple input multiple output) environment, 2D domain to be used by a terminal can be determined or used by transmitting K (>1) number of CSI-RS (reference signal) resources to which different 2D (vertical and/or horizontal) precoding is applied within a single CSI (channel state information) process. In this case, when the terminal reports CSI-RS-based CSI to a base station, it is necessary to have a method capable of reporting more accurate CSI.